I have been trying to get my c43/55 smoged for the last few months in Calif.

My issue started with the evap control not working correctly. After checking the purge valve, the vent valve and pressure testing the lines I called the dealer and asked ifthe gas tank sensor ever goes bad. There response "was almost never". So i checked more things, all the grounds, etc. Finally I took it to a indepenant that I spent some time with talking about cars and such, to check him out and he found the gas tank pressure sensor was faulty. He found this in less than one hour and replaced it. The CEL code was PO446 which is the purge valve. Prior to me spending 20 hours on this I had spent $700 at the dealer who could not find the issue and finally said it was probalby a bad ECU.

Anyhow after getting that fixed I went about driving the car and setting all the OBDII sensors so they would pass the readiness check. This took about 300 miles of driving and trying to follow the factory drive cycle.

The car was running great the engine idled well in park and drive it was all set. Short term fuel trims were between +1 to -1.

When the smog guy put the tailpipe probe in the car and revved it to 2500 rpm for 30 sec all was well, but when he took his foot off the gas the engine would not return to 750 rpm the idle speed. Instead it hung up at 1200 to 1400 rpm.

Now if you put the air cond. on the idle would drop right back down. And if you put it in gear it would drop right back down. But when you shift back to park the idle now shoots up to 1200 and sometimes to 2200 rpm.

And I have changed out thottle bodies with no change to the result. I am in desparate need of advise. I took it the the dealer and they tried to adapt the throttle body(TB) and thier best ECU guy went through all the engine parameters and they all looked good. But after trying without success to adapt the TB several times it would not complete the cycle. Now the BAS/ESP light is on and he could not pull it off and the TB plate angle is stuck at 6 degrees. I brought it in and the angle was set at 0.3 degrees.

Right now the car won't take any throttle and just surges and bucks when you put it in drive. I turned it around after driving for one block and parked it at the dealer back lot where they keep the service cars. I am going there now to replace the TB and see if I can get it home. Dealer service helper I see called and asked that I get the car off the lot.

At least when I got to the delaer the drove great except for when putting the car into park and then the idle would raise up to 1200 to 2200 rpm. Now it wont drive at all.

ANY HELP< PLEASE

Jeff

 

And this is with the 5.5L?

I was going to say the ECU, but you say it's been checked already. I once had a similar problem with my SL600 after pulling it out from service, the idle was all over the place. I took it back to the dealer and they found, that somehow, I had a oil leak with interfered with my ECU. No idea on the specifics as they just fixed it, but I'm just posting for possible leads.

I can call and have my buddy check the service records for a detailed explanation if you would like. Though again, you said your ECU was tip-top.

 

Thanks for the post. While the ECU appears to check out on several items he couldn't say that it wasn't the ECU either, at least not yet.

On the advise of Kleemann I had them install the E55 ECU code functions so the ECU data set points would match the 5.5L motor.

Do most of the guys here run the stock C43 ECU with no changes, or did you have the ECU recoded to match up with the E55 ECU data?

The tech thinks I should have the ECU sent back and have Kleemann reflash the ECU back to the stock C43 data codes and then put the reflashed stock ECU back into the car to see if he can complete all the adaptions and reset the throttle body open and close points.

Any reason to think the Kleemann flashed ECU shouldn't allow the adaption of the throttle body?

Jeff

 

I have had my 5.5 swap going on 1 1/2 years with no ECU mapping. Has the CEL come back on or the ESP? What is the ESP code? Have you received a SDS printout? How long have you been driving with the 5.5 or is it a recent swap? Diagnosing over the internet is a little difficult. Wish you were on the East coast. Excuse the questioning

 

Ive never met you jeff but I heard about you

Good to hear you are still around and are into 202s

Any chance we can get a sac meet goin so we can all get together sometime???

 

The M112 & M113 throttle bodies are electronic, there's no mechanical linkage so the throttle body is not the issue.

Sounds like you have a vacuum leak that is preventing the car from dropping back down to idle, That may also explain why the car doesn't want to go forward because its not able to meter the air properly. Check all your intake hookups and vacuum lines and make sure too much air isn't bypassing your mass air sensor.

 

Jeff for once I can say Omey Homey may be right concerning a vacuum leak somewhere.

I have not personally experienced any of the problems you are having and I've had both a new ECU programmed for an E55 in my car and the C43 ECU as well which is in my car now.
I do need to send my ECU to Kleemann to program my car for my exhaust though.

But I've never had any idling problems with my car. if you want I could also PM you Jeffrey's #.

He's fixed many members cars here on the forum where the dealer mechanics had no clue, and he also is a Pro with the Star Diag.

 

ProjectC55,

If you could get me the number for Jeffery that would be great.

The car when hooked to a vacuum gage measures approx. 20-21 in/Hg. The absolute Manifold pressure reading runs 9.8 to 10.5in/Hg.

Idle speed in Drive is 600 rpm

I dont think it is a vacuum leak but I will check it again, to make very sure.

I hook up a scanner quite a bit, do any of you record your cars ECU sensors, I would love to hear what readings you record from your engines?

I usually run a MAF value in Park of around 4.00 gms/sec. or 14 kilos/hr and when in Drive it climbs to 4.75 gms/sec or 17kilos/hr. However because my intake tubing has been machined to 81mm from 72mm stock(?) and the same for the elbow and the the throttle body housing I bored out to the same diameter and then it tapers back to stock diameter at the throttle blade and then maintains the stock diameter to the intake manifold, due the increase in diameter the MAF would only read 3.0 grams/sec except I made a electric device using a varible resistor so I can alter the MAF sesnor out to the ECU. So with the varible resistor I adjust the reading to the values shown above.

To answer on other question I have had the car for about 3.5 years and this is the first time this happened.

Thanks for all your inputs.

Jeff

 

I'd get the car to idle in the 1200-2200 RPM position, and then have someone engage the AC while I watched the e-throttle actuator. If the actuator moves enough to drop the idle, and it moves again (in the opposite direction) when the AC is turned off, the pedal sensor/actuator or some related e-throttle part may be defective.

 

Any update? I have 5.5 swapped my w215 and I have a fluctuating idle, sometimes the idle will be a bit high like 900rpm, where as I expect it to be more like 750ish

edit : more info - the car has overall ran great since the swap. In the recent months I’ve gotten some p0131/0151/0157/0137 codes I’ve been trying to track down

the idle thing is weird because sometimes the idle is fine, other times I’ll start the car and the idle will be high until I turn off the car. I’ve cleaned the throttle body, resealed the upper intake manifold, addressed most vacuum hoses, replaced fuel filter and fuel punp( however I am losing fuel pressure after shut off, so I wonder if fuel is my issue with idle). I’ve also removed cats/mufflers etc(I’ve placed the secondary o2’s outside of the exhaust stream but still get secondary o2 sensor codes?)

i think we need to remember, while our cars seem to work fine with stock ecu maps, there’s no doubting that the bigger 5.5 engine is swallowing more fuel and air..whether our stock maps can adjust for this is another question

 

Jeez, a 10 year thread revival. That must be close to a record

 

hopefully we’ve been able to figure this issue out over the past ten years! Lol

 

Those are some weak numbers, we gotta pump those numbers up

 

I love forums. Someone posts a topic. "UsE tHe SeArCh fUncTioN NOOOOOOOOOOOB" then when someone ACTUALLY searches and replies in a post. "WOW nice old thread revival loser" Like holy crap. which one is it? search or dont search,

 

for real, haha. I have no shame digging up old threads, too much valuable information and insight to be shared to care about “wow old thread”. Itd be different if these forums weren’t getting really slow and if people.replied.with.the.resolution.they.found.to.t heir.original.question.

Thats the point of forums, ask questions and build solutions. Not ask questions and dip out..

 

Search first and ask 2nd is a good forum practice IMO. Lots of good info in this old thread to review.